ng_bpf.c revision 139823 
1/*
2 * ng_bpf.c
3 */
4
5/*-
6 * Copyright (c) 1999 Whistle Communications, Inc.
7 * All rights reserved.
8 *
9 * Subject to the following obligations and disclaimer of warranty, use and
10 * redistribution of this software, in source or object code forms, with or
11 * without modifications are expressly permitted by Whistle Communications;
12 * provided, however, that:
13 * 1. Any and all reproductions of the source or object code must include the
14 *    copyright notice above and the following disclaimer of warranties; and
15 * 2. No rights are granted, in any manner or form, to use Whistle
16 *    Communications, Inc. trademarks, including the mark "WHISTLE
17 *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
18 *    such appears in the above copyright notice or in the software.
19 *
20 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
21 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
22 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
23 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
24 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
25 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
26 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
27 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
28 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
29 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
30 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
31 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
32 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35 * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
36 * OF SUCH DAMAGE.
37 *
38 * Author: Archie Cobbs <archie@freebsd.org>
39 *
40 * $FreeBSD: head/sys/netgraph/ng_bpf.c 139823 2005-01-07 01:45:51Z imp $
41 * $Whistle: ng_bpf.c,v 1.3 1999/12/03 20:30:23 archie Exp $
42 */
43
44/*
45 * BPF NETGRAPH NODE TYPE
46 *
47 * This node type accepts any number of hook connections.  With each hook
48 * is associated a bpf(4) filter program, and two hook names (each possibly
49 * the empty string).  Incoming packets are compared against the filter;
50 * matching packets are delivered out the first named hook (or dropped if
51 * the empty string), and non-matching packets are delivered out the second
52 * named hook (or dropped if the empty string).
53 *
54 * Each hook also keeps statistics about how many packets have matched, etc.
55 */
56
57#include <sys/param.h>
58#include <sys/systm.h>
59#include <sys/errno.h>
60#include <sys/kernel.h>
61#include <sys/malloc.h>
62#include <sys/mbuf.h>
63
64#include <net/bpf.h>
65
66#include <netgraph/ng_message.h>
67#include <netgraph/netgraph.h>
68#include <netgraph/ng_parse.h>
69#include <netgraph/ng_bpf.h>
70
71#ifdef NG_SEPARATE_MALLOC
72MALLOC_DEFINE(M_NETGRAPH_BPF, "netgraph_bpf", "netgraph bpf node ");
73#else
74#define M_NETGRAPH_BPF M_NETGRAPH
75#endif
76
77#define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))
78
79#define ERROUT(x)	do { error = (x); goto done; } while (0)
80
81/* Per hook private info */
82struct ng_bpf_hookinfo {
83	node_p			node;
84	hook_p			hook;
85	struct ng_bpf_hookprog	*prog;
86	struct ng_bpf_hookstat	stats;
87};
88typedef struct ng_bpf_hookinfo *hinfo_p;
89
90/* Netgraph methods */
91static ng_constructor_t	ng_bpf_constructor;
92static ng_rcvmsg_t	ng_bpf_rcvmsg;
93static ng_shutdown_t	ng_bpf_shutdown;
94static ng_newhook_t	ng_bpf_newhook;
95static ng_rcvdata_t	ng_bpf_rcvdata;
96static ng_disconnect_t	ng_bpf_disconnect;
97
98/* Internal helper functions */
99static int	ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp);
100
101/* Parse type for one struct bfp_insn */
102static const struct ng_parse_struct_field ng_bpf_insn_type_fields[] = {
103	{ "code",	&ng_parse_hint16_type	},
104	{ "jt",		&ng_parse_uint8_type	},
105	{ "jf",		&ng_parse_uint8_type	},
106	{ "k",		&ng_parse_uint32_type	},
107	{ NULL }
108};
109static const struct ng_parse_type ng_bpf_insn_type = {
110	&ng_parse_struct_type,
111	&ng_bpf_insn_type_fields
112};
113
114/* Parse type for the field 'bpf_prog' in struct ng_bpf_hookprog */
115static int
116ng_bpf_hookprogary_getLength(const struct ng_parse_type *type,
117	const u_char *start, const u_char *buf)
118{
119	const struct ng_bpf_hookprog *hp;
120
121	hp = (const struct ng_bpf_hookprog *)
122	    (buf - OFFSETOF(struct ng_bpf_hookprog, bpf_prog));
123	return hp->bpf_prog_len;
124}
125
126static const struct ng_parse_array_info ng_bpf_hookprogary_info = {
127	&ng_bpf_insn_type,
128	&ng_bpf_hookprogary_getLength,
129	NULL
130};
131static const struct ng_parse_type ng_bpf_hookprogary_type = {
132	&ng_parse_array_type,
133	&ng_bpf_hookprogary_info
134};
135
136/* Parse type for struct ng_bpf_hookprog */
137static const struct ng_parse_struct_field ng_bpf_hookprog_type_fields[]
138	= NG_BPF_HOOKPROG_TYPE_INFO(&ng_bpf_hookprogary_type);
139static const struct ng_parse_type ng_bpf_hookprog_type = {
140	&ng_parse_struct_type,
141	&ng_bpf_hookprog_type_fields
142};
143
144/* Parse type for struct ng_bpf_hookstat */
145static const struct ng_parse_struct_field ng_bpf_hookstat_type_fields[]
146	= NG_BPF_HOOKSTAT_TYPE_INFO;
147static const struct ng_parse_type ng_bpf_hookstat_type = {
148	&ng_parse_struct_type,
149	&ng_bpf_hookstat_type_fields
150};
151
152/* List of commands and how to convert arguments to/from ASCII */
153static const struct ng_cmdlist ng_bpf_cmdlist[] = {
154	{
155	  NGM_BPF_COOKIE,
156	  NGM_BPF_SET_PROGRAM,
157	  "setprogram",
158	  &ng_bpf_hookprog_type,
159	  NULL
160	},
161	{
162	  NGM_BPF_COOKIE,
163	  NGM_BPF_GET_PROGRAM,
164	  "getprogram",
165	  &ng_parse_hookbuf_type,
166	  &ng_bpf_hookprog_type
167	},
168	{
169	  NGM_BPF_COOKIE,
170	  NGM_BPF_GET_STATS,
171	  "getstats",
172	  &ng_parse_hookbuf_type,
173	  &ng_bpf_hookstat_type
174	},
175	{
176	  NGM_BPF_COOKIE,
177	  NGM_BPF_CLR_STATS,
178	  "clrstats",
179	  &ng_parse_hookbuf_type,
180	  NULL
181	},
182	{
183	  NGM_BPF_COOKIE,
184	  NGM_BPF_GETCLR_STATS,
185	  "getclrstats",
186	  &ng_parse_hookbuf_type,
187	  &ng_bpf_hookstat_type
188	},
189	{ 0 }
190};
191
192/* Netgraph type descriptor */
193static struct ng_type typestruct = {
194	.version =	NG_ABI_VERSION,
195	.name =		NG_BPF_NODE_TYPE,
196	.constructor =	ng_bpf_constructor,
197	.rcvmsg =	ng_bpf_rcvmsg,
198	.shutdown =	ng_bpf_shutdown,
199	.newhook =	ng_bpf_newhook,
200	.rcvdata =	ng_bpf_rcvdata,
201	.disconnect =	ng_bpf_disconnect,
202	.cmdlist =	ng_bpf_cmdlist,
203};
204NETGRAPH_INIT(bpf, &typestruct);
205
206/* Default BPF program for a hook that matches nothing */
207static const struct ng_bpf_hookprog ng_bpf_default_prog = {
208	{ '\0' },		/* to be filled in at hook creation time */
209	{ '\0' },
210	{ '\0' },
211	1,
212	{ BPF_STMT(BPF_RET+BPF_K, 0) }
213};
214
215/*
216 * Node constructor
217 *
218 * We don't keep any per-node private data
219 * We go via the hooks.
220 */
221static int
222ng_bpf_constructor(node_p node)
223{
224	NG_NODE_SET_PRIVATE(node, NULL);
225	return (0);
226}
227
228/*
229 * Add a hook
230 */
231static int
232ng_bpf_newhook(node_p node, hook_p hook, const char *name)
233{
234	hinfo_p hip;
235	int error;
236
237	/* Create hook private structure */
238	MALLOC(hip, hinfo_p, sizeof(*hip), M_NETGRAPH_BPF, M_NOWAIT | M_ZERO);
239	if (hip == NULL)
240		return (ENOMEM);
241	hip->hook = hook;
242	NG_HOOK_SET_PRIVATE(hook, hip);
243	hip->node = node;
244
245	/* Attach the default BPF program */
246	if ((error = ng_bpf_setprog(hook, &ng_bpf_default_prog)) != 0) {
247		FREE(hip, M_NETGRAPH_BPF);
248		NG_HOOK_SET_PRIVATE(hook, NULL);
249		return (error);
250	}
251
252	/* Set hook name */
253	strncpy(hip->prog->thisHook, name, sizeof(hip->prog->thisHook) - 1);
254	hip->prog->thisHook[sizeof(hip->prog->thisHook) - 1] = '\0';
255	return (0);
256}
257
258/*
259 * Receive a control message
260 */
261static int
262ng_bpf_rcvmsg(node_p node, item_p item, hook_p lasthook)
263{
264	struct ng_mesg *msg;
265	struct ng_mesg *resp = NULL;
266	int error = 0;
267
268	NGI_GET_MSG(item, msg);
269	switch (msg->header.typecookie) {
270	case NGM_BPF_COOKIE:
271		switch (msg->header.cmd) {
272		case NGM_BPF_SET_PROGRAM:
273		    {
274			struct ng_bpf_hookprog *const
275			    hp = (struct ng_bpf_hookprog *)msg->data;
276			hook_p hook;
277
278			/* Sanity check */
279			if (msg->header.arglen < sizeof(*hp)
280			    || msg->header.arglen
281			      != NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len))
282				ERROUT(EINVAL);
283
284			/* Find hook */
285			if ((hook = ng_findhook(node, hp->thisHook)) == NULL)
286				ERROUT(ENOENT);
287
288			/* Set new program */
289			if ((error = ng_bpf_setprog(hook, hp)) != 0)
290				ERROUT(error);
291			break;
292		    }
293
294		case NGM_BPF_GET_PROGRAM:
295		    {
296			struct ng_bpf_hookprog *hp;
297			hook_p hook;
298
299			/* Sanity check */
300			if (msg->header.arglen == 0)
301				ERROUT(EINVAL);
302			msg->data[msg->header.arglen - 1] = '\0';
303
304			/* Find hook */
305			if ((hook = ng_findhook(node, msg->data)) == NULL)
306				ERROUT(ENOENT);
307
308			/* Build response */
309			hp = ((hinfo_p)NG_HOOK_PRIVATE(hook))->prog;
310			NG_MKRESPONSE(resp, msg,
311			    NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len), M_NOWAIT);
312			if (resp == NULL)
313				ERROUT(ENOMEM);
314			bcopy(hp, resp->data,
315			   NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len));
316			break;
317		    }
318
319		case NGM_BPF_GET_STATS:
320		case NGM_BPF_CLR_STATS:
321		case NGM_BPF_GETCLR_STATS:
322		    {
323			struct ng_bpf_hookstat *stats;
324			hook_p hook;
325
326			/* Sanity check */
327			if (msg->header.arglen == 0)
328				ERROUT(EINVAL);
329			msg->data[msg->header.arglen - 1] = '\0';
330
331			/* Find hook */
332			if ((hook = ng_findhook(node, msg->data)) == NULL)
333				ERROUT(ENOENT);
334			stats = &((hinfo_p)NG_HOOK_PRIVATE(hook))->stats;
335
336			/* Build response (if desired) */
337			if (msg->header.cmd != NGM_BPF_CLR_STATS) {
338				NG_MKRESPONSE(resp,
339				    msg, sizeof(*stats), M_NOWAIT);
340				if (resp == NULL)
341					ERROUT(ENOMEM);
342				bcopy(stats, resp->data, sizeof(*stats));
343			}
344
345			/* Clear stats (if desired) */
346			if (msg->header.cmd != NGM_BPF_GET_STATS)
347				bzero(stats, sizeof(*stats));
348			break;
349		    }
350
351		default:
352			error = EINVAL;
353			break;
354		}
355		break;
356	default:
357		error = EINVAL;
358		break;
359	}
360done:
361	NG_RESPOND_MSG(error, node, item, resp);
362	NG_FREE_MSG(msg);
363	return (error);
364}
365
366/*
367 * Receive data on a hook
368 *
369 * Apply the filter, and then drop or forward packet as appropriate.
370 */
371static int
372ng_bpf_rcvdata(hook_p hook, item_p item)
373{
374	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
375	int totlen;
376	int needfree = 0, error = 0;
377	u_char *data, buf[256];
378	hinfo_p dhip;
379	hook_p dest;
380	u_int len;
381	struct mbuf *m;
382
383	m = NGI_M(item);	/* 'item' still owns it.. we are peeking */
384	totlen = m->m_pkthdr.len;
385	/* Update stats on incoming hook. XXX Can we do 64 bits atomically? */
386	/* atomic_add_int64(&hip->stats.recvFrames, 1); */
387	/* atomic_add_int64(&hip->stats.recvOctets, totlen); */
388	hip->stats.recvFrames++;
389	hip->stats.recvOctets += totlen;
390
391	/* Need to put packet in contiguous memory for bpf */
392	if (m->m_next != NULL) {
393		if (totlen > sizeof(buf)) {
394			MALLOC(data, u_char *, totlen, M_NETGRAPH_BPF, M_NOWAIT);
395			if (data == NULL) {
396				NG_FREE_ITEM(item);
397				return (ENOMEM);
398			}
399			needfree = 1;
400		} else
401			data = buf;
402		m_copydata(m, 0, totlen, (caddr_t)data);
403	} else
404		data = mtod(m, u_char *);
405
406	/* Run packet through filter */
407	if (totlen == 0)
408		len = 0;	/* don't call bpf_filter() with totlen == 0! */
409	else
410		len = bpf_filter(hip->prog->bpf_prog, data, totlen, totlen);
411	if (needfree)
412		FREE(data, M_NETGRAPH_BPF);
413
414	/* See if we got a match and find destination hook */
415	if (len > 0) {
416
417		/* Update stats */
418		/* XXX atomically? */
419		hip->stats.recvMatchFrames++;
420		hip->stats.recvMatchOctets += totlen;
421
422		/* Truncate packet length if required by the filter */
423		/* Assume this never changes m */
424		if (len < totlen) {
425			m_adj(m, -(totlen - len));
426			totlen -= len;
427		}
428		dest = ng_findhook(hip->node, hip->prog->ifMatch);
429	} else
430		dest = ng_findhook(hip->node, hip->prog->ifNotMatch);
431	if (dest == NULL) {
432		NG_FREE_ITEM(item);
433		return (0);
434	}
435
436	/* Deliver frame out destination hook */
437	dhip = NG_HOOK_PRIVATE(dest);
438	dhip->stats.xmitOctets += totlen;
439	dhip->stats.xmitFrames++;
440	NG_FWD_ITEM_HOOK(error, item, dest);
441	return (error);
442}
443
444/*
445 * Shutdown processing
446 */
447static int
448ng_bpf_shutdown(node_p node)
449{
450	NG_NODE_UNREF(node);
451	return (0);
452}
453
454/*
455 * Hook disconnection
456 */
457static int
458ng_bpf_disconnect(hook_p hook)
459{
460	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
461
462	KASSERT(hip != NULL, ("%s: null info", __func__));
463	FREE(hip->prog, M_NETGRAPH_BPF);
464	bzero(hip, sizeof(*hip));
465	FREE(hip, M_NETGRAPH_BPF);
466	NG_HOOK_SET_PRIVATE(hook, NULL);			/* for good measure */
467	if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
468	&& (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) {
469		ng_rmnode_self(NG_HOOK_NODE(hook));
470	}
471	return (0);
472}
473
474/************************************************************************
475			HELPER STUFF
476 ************************************************************************/
477
478/*
479 * Set the BPF program associated with a hook
480 */
481static int
482ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp0)
483{
484	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
485	struct ng_bpf_hookprog *hp;
486	int size;
487
488	/* Check program for validity */
489	if (!bpf_validate(hp0->bpf_prog, hp0->bpf_prog_len))
490		return (EINVAL);
491
492	/* Make a copy of the program */
493	size = NG_BPF_HOOKPROG_SIZE(hp0->bpf_prog_len);
494	MALLOC(hp, struct ng_bpf_hookprog *, size, M_NETGRAPH_BPF, M_NOWAIT);
495	if (hp == NULL)
496		return (ENOMEM);
497	bcopy(hp0, hp, size);
498
499	/* Free previous program, if any, and assign new one */
500	if (hip->prog != NULL)
501		FREE(hip->prog, M_NETGRAPH_BPF);
502	hip->prog = hp;
503	return (0);
504}
505
506